High-Temperature In situ Deformation of GaAs Micro-pillars: Lithography Versus FIB Machining

Chen, M.; Wehrs, J.; Michler, J.; Wheeler, J. M.

Jom 68 (2016)

The plasticity of silicon-doped GaAs was investigated between 25°C and 400°C using microcompression to prevent premature failure by cracking. Micropillars with diameters of ~2.5 μm were fabricated on a ⟨ 100 ⟩ -oriented GaAs single crystal by means of both conventional lithographic etching techniques and focused ion beam machining and then compressed in situ in the scanning electron microscope (SEM). A transition in deformation mechanisms from partial dislocations to perfect dislocations was found at around 100°C. At lower temperatures, the residual surface layer from lithographic processing was found to provide sufficient constraint to prevent crack opening, which resulted in a significant increase in ductility over FIB-machined pillars. Measured apparent activation energies were found to be significantly lower than previous bulk measurements, which is mostly attributed to the silicon dopant and to a lesser extent to the size effect.